High-frequency layered part and manufacturing method thereof

ABSTRACT

The present invention relates to a high frequency laminated component, which is used in a high frequency apparatus such as a radio communication apparatus, and its manufacturing method. An object thereof is to downsize the high frequency laminated component. To achieve the object, according to the high frequency laminated component of the present invention, dielectric layer ( 4 ) whose dielectric constant is lower than that of other areas is formed around via-hole electrode ( 3 ) in a dielectric. By forming dielectric layer ( 4 ) having a low dielectric constant, electric interference between via-hole electrode ( 3 ) and circuit electrode ( 22 ) is restrained, so that the circuit electrode and the via-hole electrode can be formed more closely each other compared with a conventional one. As a result, the high frequency laminated component can be downsized.

TECHNICAL FIELD

The present invention relates to a high frequency laminated component,which is used in a high frequency apparatus such as a radiocommunication apparatus, and its manufacturing method.

BACKGROUND ART

In general, a high frequency component, which is used in a highfrequency apparatus such as a high frequency filter or a high frequencyswitch, forms a high frequency circuit by positioning a plurality ofcircuit electrodes between layers of a multilayer substrate made ofdielectric material and connecting these circuit electrodes through avia-hole electrode.

This high frequency laminated component is formed as following steps:Forming the circuit electrodes and the via-hole electrode at adielectric sheet which is not sintered, and then piling and baking theplurality of dielectric sheets.

Japanese Patent Unexamined Publication H9-214274 is known as a prior artinformation in this technical field.

Recently, this high frequency laminated component has been required tobe more downsized.

SUMMARY OF THE INVENTION

According to a high frequency laminated component of the presentinvention, in a multilayer substrate, a dielectric around a via-holeelectrode has a lower dielectric constant than that of other areas.Using the structure discussed above, electric interference between acircuit electrode and the via-hole electrode is restrained, so that thecircuit electrode and the via-hole electrode can be formed more closelyeach other compared with a conventional one. As a result, the highfrequency laminated component can be downsized.

In addition, according to a method of manufacturing the high frequencylaminated component of the present invention, low-temperature sinteringmaterial where a glass ingredient is contained in dielectric material isused as a dielectric sheet forming a dielectric layer, and a via-hole isformed by a laser in a boring process. Using the method discussed above,the glass ingredient is deposited at an inner circumference of thevia-hole.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a high frequency laminated component inaccordance with an exemplary embodiment of the present invention.

FIG. 2 is a sectional view of an essential part of the high frequencylaminated component showing a via-hole electrode in accordance with theexemplary embodiment of the present invention.

FIG. 3 is a schematic view showing a boring process of the highfrequency laminated component in accordance with the exemplaryembodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

When a high frequency laminated component is structured, a circuitelectrode is formed horizontally and a via-hole electrode is formedvertically in a multilayer substrate having a certain dielectricconstant, so that the circuit electrode and the via-hole electrode areeasily interfered with each other. In general, the via-hole electrodeand the circuit electrode, which is not directly connected thereto, haveto be placed separately each other at a certain distance for restrainingthe mutual interference therebetween. On the contrary, according to ahigh frequency laminated component of the present invention, adielectric layer (i.e., a first dielectric layer) around a via-holeelectrode has a lower dielectric constant than that of other areas, sothat the high frequency laminated component can be downsized.

Exemplary embodiments are demonstrated hereinafter with reference toaccompanying drawings.

Exemplary Embodiment

FIG. 1 is a sectional view of a high frequency laminated component usedin a high frequency apparatus such as a high frequency filter or a highfrequency switch. Circuit electrodes 21, 22 and 23, which forms a highfrequency circuit, and via-hole electrode 3, which couples circuitelectrodes 21 and 23, are formed inside multilayer substrate 100 made ofdielectric 10.

Next, a method of manufacturing the high frequency laminated componentis described hereinafter.

First, a via-hole for via-hole electrode 3 is formed at a certainposition of a dielectric sheet which forms dielectric layer 11 (i.e., asecond dielectric layer) of multilayer substrate 100. Second, thevia-hole is filled with electrode paste, and circuit electrodes 21, 22and 23 are applied on dielectric layer 11. Third, the dielectric sheets,where circuit electrodes 21-23 and via-hole electrode 3 are formed, arepiled so as to construct a laminated member. Last, the laminated member10 is baked, whereby the high frequency laminated component iscompleted.

When ceramic material containing low-melting glass is used as materialof the dielectric sheet forming dielectric layer 11, the dielectricsheet and the electrode paste can be simultaneously baked.

According to the manufacturing method of the present invention, a laseris used in a boring process for forming via-hole electrode 3 in thedielectric sheet. By forming the via-hole using the laser, a glassingredient which has been contained in the dielectric sheet is depositedat an inner circumference of the via-hole, so that a glass layer isformed at a circumference of via-hole electrode 3.

Specifically, in a case where material of the dielectric sheet is formedof dielectric material which has a dielectric constant of approximately10 and contains glass having a dielectric constant of approximately 5, adielectric constant of the dielectric sheet after baking becomesapproximately 7. On the other hand, low dielectric layer 4 (i.e., afirst dielectric layer), which is formed of glass having a dielectricconstant of approximately 5, is formed with a certain thickness nearvia-hole electrode 3 bored by the laser.

Therefore, via-hole electrode 3 extending vertically in multilayersubstrate 100 is surrounded with low dielectric layer 4. Accordingly,mutual interference between circuit electrode 22 and via-hole electrode3 is restrained, though circuit electrode 22 is formed horizontally andtwo dimensionally for dielectric layer 11 and easy to be electricallycontacted with via-hole electrode 3. As a result, the high frequencylaminated component can be downsized because circuit electrode 22 andvia-hole electrode 3 can be formed closely each other compared with aconventional one.

A carbon dioxide laser having a great power is preferably used as thelaser in the boring process. Deposition of the glass becomes greater byusing the great power laser, so that low dielectric layer 4 can beformed thicker.

On the other hand, in the high frequency laminated component discussedabove, according to development of a high frequency of a frequency bandand downsizing of a frequency component in recent years, via-holeelectrode 3, which was conventionally used only as an electrode forconnecting, has been utilized as inductance. Therefore, high impedanceof via-hole electrode 3 is necessary for forming inductance.

In a word, electrical coupling between an earth electrode, which is oneof circuit electrodes 21, 22 and 23 formed in multilayer substrate 100,and via-hole electrode 3 is restrained by surrounding via-hole electrode3 with low dielectric layer 4 for performing high impedance.Accordingly, via-hole electrode 3 can be effectively utilized asinductance.

In addition, according to the high frequency laminated component of thepresent embodiment, a diameter of via-hole electrode 3, which is formedacross multilayered dielectric layers 11, is not constant in a directionof thickness. At a connecting point of via-hole electrodes 3 betweendielectric layers 11, an upper part of via-hole electrodes 3 differsfrom a lower part thereof in a diameter. As shown in FIG. 2 which is anenlarged view of a part of the via-hole, the via-hole formed throughdielectric layers 111 and 112 is processed to be tapered from an upperside to a lower side. As a result, at a connecting point betweenvia-hole electrodes 31 and 32, which are formed by filling two via-holeswith an electric conductor, diameter D2 of via-hole electrode 32 islarger than diameter D1 of via-hole electrode 31. Besides, via-holeelectrodes 31 and 32 are respectively surrounded with low dielectriclayers 41 and 42.

Using the structure discussed above, SIR (Step-Impedance-Resonator)effect that impedance varies inside a series of via-hole electrode 3 isinduced, so that greater inductance can be added to via-hole electrode3.

As discussed above, as the method for forming different diameters at theupper part and the lower part of the connecting point of via-holeelectrodes 3, converged beam 5 of the laser can be used in the boringprocess of the dielectric sheet as shown in a broken line of FIG. 3.Using the method shown in FIG. 3, via-hole 7 having taper for dielectricsheet 6 is easy to be manufactured without using a particular process.

In a word, in a case where the via-hole electrode is formed across theplurality of dielectric layers, inductance formed of the via-holeelectrode itself becomes greater by changing impedance at the connectingpoint between dielectric layers. As a result, the high frequencylaminated component can be more downsized.

According to the high frequency laminated component of the presentembodiment discussed above, all high frequency components areconstructed by circuit electrodes 21 and 22 formed in multilayersubstrate 100. However, the same effect can be obtained by mountingactive components such as a diode or a FET on multilayer substrate 100for structuring a certain kind of high frequency component.

INDUSTRIAL APPLICABILITY

According to the present invention discussed above, a dielectricconstant near a via-hole electrode is formed to be lower than that ofother areas in a multilayer substrate, so that interference between acircuit electrode and the via-hole electrode can be restrained. As aresult, a downsized high frequency laminated component can be providedbecause the circuit electrode and the via-hole electrode can be formedclosely each other compared with a conventional one.

1. A high frequency laminated component including: a plurality ofcircuit electrode layers; a dielectric for surrounding the electrodelayers; a via-hole for penetrating the dielectric; and a via-holeelectrode, which is formed of an electric conductor to be filled in thevia-hole, for coupling the electrode layers, the high frequencylaminated component comprising: a first dielectric layer, which has alower dielectric constant than the dielectric, being formed around thevia-hole electrode.
 2. The high frequency laminated component of claim1, wherein the dielectric is formed of a plurality of second dielectriclayers, and the via-hole electrode, which is formed through theplurality of second dielectric layers, has different impedance at aconnecting point between the second dielectric layers.
 3. The highfrequency laminated component of claim 2, wherein a second dielectriclayer of the second dielectric layers has a first surface and a secondsurface, and the via-hole formed in the second dielectric layer hasdifferent diameters at the first surface and the second surface.
 4. Thehigh frequency laminated component of claim 1, wherein an internaldiameter of the via-hole changes in a direction of thickness.
 5. Thehigh frequency laminated component of claim 1, the dielectric is made oflow-temperature sintering material where a glass ingredient is containedin dielectric material.
 6. A method of manufacturing a frequencylaminated component comprising: a boring step for forming a via-hole ina dielectric sheet; a printing step for forming a circuit electrode onthe dielectric sheet; and a laminating step for laminating thedielectric sheets, wherein the dielectric sheet is made oflow-temperature sintering material where a glass ingredient is containedin dielectric material, and the glass ingredient is deposited at aninner circumference of the via-hole by boring the dielectric sheet usinga laser in the boring step.
 7. The method of manufacturing the frequencylaminated component of claim 6, wherein the laser is a carbon dioxidelaser.
 8. The method of manufacturing the frequency laminated componentof claim 6, wherein the boring step is performed by using a convergedbeam of the laser, wherein the via-hole has a first opening at a firstsurface of the dielectric sheet and a second opening at a second surfaceof the dielectric sheet, and the via-hole is processed so that the firstopening and the second opening have different diameters each other. 9.The method of manufacturing the frequency laminated component of claim8, wherein adjacent the first opening and the second opening of thedielectric sheet are coupled with each other at the laminating step.